Comments on taxonomy:Tribe:Ardeini. There are 6 subspecies of great egrets with only C.a. egretta occurring in North America *04*. Other names:common egret, American egret, angel bird, long white, great white egret, white crane, plumebirds, greater egret, white egret *04,08*.

Comments on status:The great egret was included on the Illinois Endangered Species List in 1977 *01*. Historically it experienced a major decline because of plume hunting which was followed by recovery and major expansion beginning in 1937 and then a steady decline resulting in an 80% decrease in population between 1973 & 1976 *01*. This species qualifies for inclusion as an endangered species due to: 1) its recent decline 2)small population numbers 3)habitat destruction *01*.

Comments on species-habitat associations:The great egret requires 2 distinct habitat types for survival: 1) foraging habitat in unpolluted wetland situations; 2) nesting habitat, usually near foraging habitat, containing either trees or shrubs that provide enough support and building materials (twigs) for the nest *01,04,07*. Large herons seem to choose the largest trees for nesting but a wide variety of species and sizes are utilized *01*. In Illinois several particular species occur in favorable sites and are utilized by herons *06,07,11*. See comments on important plant/animal assoc.

Important plant and animal association: In Illinois, the great egret is associated with silver maple, cottonwood, black willow, slippery elm and green ashe as characteristic species present in its breeding habitat *06,07,11*. Gizzard shad seem to be the principal fish species consumed in Illinois *01,03,13*.

High value habitats

Habitat

Structural stage

Season

Cropland and pasture

Special habitat

Fall

Water

Special habitat

Spring

Water

Special habitat

Summer

Water

Special habitat

Fall

Wetland

Special habitat

Spring

Wetland

Special habitat

Summer

Wetland

Special habitat

Fall

Wet floodplain forest

Special habitat

Spring

Wet floodplain forest

Special habitat

Summer

Wet floodplain forest

Special habitat

Fall

Marsh

Special habitat

Spring

Marsh

Special habitat

Summer

Marsh

Special habitat

Fall

Swamp

Special habitat

Spring

Swamp

Special habitat

Summer

Swamp

Special habitat

Fall

Shrub swamp

Special habitat

Spring

Shrub swamp

Special habitat

Summer

Shrub swamp

Special habitat

Fall

Lakes and ponds

Special habitat

Spring

Lakes and ponds

Special habitat

Summer

Lakes and ponds

Special habitat

Fall

Streams

Special habitat

Spring

Streams

Special habitat

Summer

Streams

Special habitat

Fall

Marsh restoration

Special habitat

Spring

Marsh restoration

Special habitat

Summer

Marsh restoration

Special habitat

Fall

Species-habitat interrelations: Lowland forest & wetland situations are essential for the great egret. Two habitat types must be present for the breeding success of this species: 1) shallow, clear lagoons, backwaters, marshes, ponds etc. Provide foraging sites; 2) lowland forest, thickety growth forms that provide support and sticks/twigs for building material are essential for nesting habitat *01,02,04,07*.

Comments on feed-guilding:The great egret is a wading bird that utilizes wetlands as its primary source of food; fish, crustaceans, frogs, snakes, and insects. Mudflats are also utilized *01,03,04,05,08,11,12,13*. The great egret is a carnivore but some vegetable matter may be taken as extraneous matter with animal food *05*. Although the foraging of the great egret has not been defined precisely it is considered to be similar to that of the great blue heron *03*.

Comments on breed-guilding:The great egret is a very social species and invariably nests colonially with other herons *03,04,05,08*. The larger herons prefer to nest in largest trees available and when the great blue heron is not present the great egret usually occupies the highest nest sites *07,11,15*. Heights may vary depending on plant species present *13*. The nest site requires adequate support and suitable supply of twigs/ sticks for building materials *04,05*. Nest sites are almost always found near water or foraging site *04,08*.

Comments on food habits: General: In Illinois the great egrets principal food item seems to be gizzard shad *01,03,11*. Other food items include fish, frogs, crayfish, snakes, insects and some small mammals *04,05,08,11,12,13*. Some vegetable matter may be taken extraneously with animal food *05*.Juvenile: Food of juveniles seems identical to adults with the exception of size. Food size increases as heron grows *03*.Adult: See comments on general food habits.

Comments on environmental associations:General: Unpolluted and undisturbed foraging sites are critical to all wading birds. The great egret must have foraging sites and nest site habitat *see card 5920* for one without the other is insufficient for heron survival *01,06,07*. Because of drainage & development, wetlands are considered a limitng factor as are the decreasing floodplain forests in Illinois *01*.Feeding juvenile: Foraging areas that are free from pollution, and disturbance are critical for the great egret *01*. These include shallow clear lagoons, backwaters, marshes, along streams and rivers, mudflats.Resting juvenile: Juveniles use the nest site for a while and then move to communal roost trees *03,04,05*. Trees are usually located in woods of swamps, floodplain forests and may be a considerable distance from foraging areas *03,04,05*.Feeding adult: See comments on feeding juvenile.Resting adult: The great egret is highly gregarious and utilizes communal roost trees at night *03,04,05*. Favored roosting places are where large numbers of birds congregate, may be near to or far from foraging sites *05*.Breeding adult: As a breeding bird the great egret requires unpolluted and undisturbed wetland situations as foraging sites and floodplain forest or a thickety growth from that provides adequate support and suitable supply of sticks/twigs for a nesting site *01,04,07*.

Reproduction: Seasonal monogamy is probably the rule *04*. Little is known about the great egrets nesting activities for Illinois. Great egrets are migratory and are usually seen along larger river systems in Illinois by late March-early April *03*. It has been reported that near East St. Louis nests were occupied by 7 April and in northern Illinois nests were occupied by 5 April *03*. The start of breeding activities is accompanied by a change in color of the soft parts of great egrets *04*, but no time table is available for Illinois. Great egrets often nest with other herons, particularly great blue and black-crowned night-herons. In Fla., males only select territories several weeks after arrival and display. Females are attracted to the vicinity by the displaying males but are not immediately receptive *04*. Information about pair-formation is unavailable. It is assumed ritualized as in other heron species *00*. Time required for nest construction unknown. Dates of nest construction include 13 March, Fla. and 17 Apr., Mich. *04*. Copula- tion takes place on males territory and if similar to other heron species, in or near nest site *04*. The nest is made of sticks/twigs or stems constructed into a flimsy platform *04,05,08,13*. It varies in location from 1 ft.-50 ft. (extreme 80 ft.) Depending on habitat available *01*. The great egret usually tries to nest as high as possible in the largest available plant species and only nests below the great blue heron *01,03,11,15*. In Illinois, great egrets frequent bottomland forest and cottonwoods, silver maple and green ash are the principal tree species utilized *06,07,11*. Most colonies are over water during part or all of nesting season. Laying frequency and clutch size are unavailable for Illinois *03*. Egg laying period has been estimated from 20 April- 14 June in southern Illinois *03*. Egg laying occurs in Feb. in Louisiana, April in Michigan, early April-early June in Maryland, 1st wk of may in South Carolina and begins in January in Florida and may continue through May *04,08*. Eggs are pale greenish blue, 56.5 x 40.5 mm *05,13*. The best estimate for Illinois is 2.2-2.5 eggs/ nest *03*. Great egrets usually lay 3-4 (1-6) eggs *04,05,08,09,12*. Other averages include; Fla. (2.8); Ga. (3.0), A (3.2), La. (2.9), Tx. (2.7). Ave. clutch size apparently increases from approx. 3 to 3- 4 moving northward from gulf states *04*. Kahl (1963) estimated 2.9 eggs/nest needed per pair to maintain a population *09*. In Fla. the interval between eggs is slightly less than 2 days (1.9 + Or - 0.37) *14*. Great egrets will lay a replacement clutch if the original is destroyed *14*. Maxwell & Kale (1977) report incubation begins with the first egg 55% and the 2nd egg 45% *14*. Both male and female incubate. Great egrets perform an elaborate relief ceremony according to Bent (1926) *05*. The incubation period for Illinois is 25 days *01*, Palmer (1962) & Bent (1926) both state 23-24 days and Sprunt & Chamberlain (1970) & Forbush (1929) both report 28 days *01,04,05,12,13*. In Fla. hatching occurred over 5.2 (1-7) days for 2.6 eggs with a 2 day interval between eggs *14*. Upon hatching nestlings are partially covered with long white down *04,05,10*. Teal (1964) reports young leave nest 2-3 weeks after hatching in Ga. *10*. In Illinois, nestling life lasts 42 days and also Palmer (1962) & Terres (1980) state first flight occurs 42 days after hatching *04,08*. Great egrets probably raise 1 brood/year *04,12,13*. Young are fed by regurgitation at first into the nest, followed by bill-grabbing similar to other heron species *05*. Kahl (1963) states that most great egrets are capable of breeding at 2 years old (or 3rd summer) *09*.

Behavior: The great egret is not usually sighted in Illinois until approx. 20 March *03*. In Fla., male alone selects territory which is used for hostile and sexual displays, copulation and nesting *04*. Adjacent feeding areas are also vigorously defended against all other smaller species of herons (not great blue heron) *04*. Both sexes defend this territory. Size is not known. No information is available on home range but Graber's (1978) report great egrets feeding usually within 9.6 km of their nesting colonies *01,03*. Great egrets are diurnal feeders, gathering at dusk in communal roost trees where they spend the night. Specific roosting trees are usually favored and may be near or a considerable distance from foraging areas *03*. The great egret exhibits extensive post-breeding dispersal and usually the young birds indulge in the erratic journeys *05*. There appear to be 2 summer populations in Illinois: 1) the Illinois breeding population that arrives in spring; 2) a population that arrives in summer from the south where nesting starts and finishes much earlier *03*. Coffey (1943) banded juvenile great egrets in Miss. and recovered 5 birds in Illinois in July & Aug. This may illustrate a northern movement *03*. Whether birds breeding in Illinois move northward has not been established but is suggested in the banding records of Bjorklund & Canterberry (1971) *03*. Transient great egrets seem to prefer the Illinois River over the Mississippi River and western to eastern Illinois *03*. Most great egrets have migrated south of Illinois by the end of October, though individuals have been reported as late as December *03*.

Limiting factors:: There are no documented figures on population size in Illinois. In 1976, 8 major colonies with approx. 100 nests remained in western and southern parts of Illinois including Bureau, Calhoun, Mason, Mercer, Monroe, Tazewell, Union & Will Counties. Recent breeding accounts for 1983 include approx. 4 colonies, 68 nests including Lake, Madison, Mercer, Mason with the largest colony of 61 nests at Clear Lake *17*. One of the largest heronries (820 occupied nests in 1962) in Tazewell Co. collapsed in 1974. It had existed since at least 1935 and great egrets arrived early April 13th (a 10 yr. Ave.) *06*. It is suggested that clear- cutting of trees, partial draining of a floodplain lake and pollution from various sources reduced the number of feeding habitats available to herons *01*. The great egret population has declined 80% between 1973-1976 *03*. Probably the most significnt cause of decline is habitat encroachment by man *01*. Predators include racoons, crows, vultures, with racoons being the most formidable *05,19*. Great egrets are also susceptible to eggshell thinning caused by hydrocarbons and the continuing use of persistent pesticides *01,19*.

Population parameters: An estimated trend from the literature leaves great egret populations down in Illinois though no recent figures are available *00*. The 80% decline experienced by great egrets between 1973-1976 probably involved movement to other areas but Bjorklund (1975) had observed what seemed to be increased egg and nestling mortality in locations altered (after logging) in Tazewell Co. *06*. The best estimate of eggs layed/nest for Illinois is 2.5- 2.2 *06*. Kahl (1963) states 2.9 eggs/nest are needed per pair to at least maintain a population *09*. Mortality rates for the great egret are approx. 76% the first year and 26% for subsequent years *09*. Life expectancy is approx. 1.4 yrs. and at the start of an individual's 2nd yr. life expectancy increases to 3.3 yrs. *09*. The oldest bird recovered was in Ohio at the age of 22 yrs. 7 mos. *08*. Age ratios for southern Illinois are 1.0 adults to 1.25 young at fledging and the ratio of spring to fall numbers are 1.0 (Mar.-May) to 12.9 (July-Oct.), a suggestion of post-breeding dispersal *03*.

Comments on management practices:It is essential to protect both the foraging areas and nesting habitat of the great egret from pollution, disturbance, and human presence. One without the other is insufficient for heron survival and the continuation of the great heron as a breeding bird in Illinois *01,06, 07*. Sanctuaries are the best means of preserving habitat *19*. The great egret is protected by the Endangered Species Act of 1977 *01*. Also the Migratory Bird Treaty Act of 1918 *20* and the Illinois Wildlife Code 1971 *21*.